The present invention relates to a turbomachine in accordance with the features described below.
More particularly, this invention relates to a turbomachine with at least one stator and at least one downstream rotor, with the stator being provided with stationary stator blades and the rotor comprising several rotor blades attached to a rotating shaft. A casing exists which confines the passage of fluid through the rotor and the stator in the outward direction.
The aerodynamic loadability and the efficiency of turbomachines, for example, blowers, compressors, pumps and fans, is limited especially by the growth and the separation of boundary layers in the rotor tip area near the casing wall. The state of the art only partly provides solutions to this problem. While various concepts for the fluid supply on turbine blades exist, these are not applicable to turbomachines since they primarily serve for surface cooling, not for boundary layer energization. For rotors, a concept exists for the supply of air on the hub and casing via axially symmetrical slots to influence the wall boundary layers there. Finally, publications exist showing concepts in which rotors are blown by individual nozzles near the casing to favorably influence the radial gap flow there. Accordingly, the general concept of influencing the boundary layer by blowing in or supplying fluid is provided in the state of the start, but the known solutions are trivial, only partly effective and very limited in their practical applicability.
FIG. 1 shows a schematic representation of the state of the art of in-service turbomachinery in the example of a multi-stage configuration. The figure schematically shows a hub 1 and a casing 2 between which a fluid flow passes from the left-hand side, as indicated by the arrow 3. Furthermore, the figure illustrates two and a half stages of a multi-stage turbomachine in cutout view, here beginning with a stator 4 and ending with a stator 6. Arranged between the stators are the rotors 7 and 8. The first stators 4, 5 shown are variable (10) to provide for an adequate operating range of the turbomachine. In support of this and serving the same purpose, a fluid bleeding device 9 is provided between the stages. These design features incur high cost and constructional effort.
The state of the art is disadvantageous in that realizable turbomachines involve considerable cost and constructional effort to ensure an adequately wide operating range, in particular, at partial load. Simple existing concepts for blowing rotor tips are not compatible with a multi-stage design since they require additional space and do not satisfy the demands of operational safety.